This invention relates to the production of plain-carbon steel having yield strength levels with attendant good ductility and weldability characteristics which, in combination, have not been economically attainable heretofore. More specifically this invention relates to the production of plain carbon steel having yield strengths in the range of 55 to 80 ksi (379-551 MPa), ductilities, as measured by percent of elongation in 2 inches (5.08 cm) of 25 to 10%, and the ease of weldability of other plain carbon steels.
With an increased emphasis in the automotive industry for pollution control and safety devices, there exists a desideratum for reducing the overall weight of automobiles. Such desideratum may be at least partially satisfied by providing means for maintaining or increasing the strength of steel components without adding to the overall weight. However, in order to accomplish this, the steel must also be capable of being readily formable into required configurations, some of which are rather complex, and also must be easily weldable to facilitate mass production. It is with this desideratum in mind that the present invention was developed.